In a power source circuit that converts an input voltage supplied from a power supply system to a predetermined voltage, the input voltage sometimes drops abruptly due to a change of input voltage sources when a power outage occurs, or the like. In order to prepare such a situation, a power source circuit including a boost converter that boosts the input voltage is provided. Also, there is a problem in that if a boost converter is operated all the time, the transmission efficiency of the power deteriorates, or noise occurs. Accordingly, a proposal has been made of a power source circuit that stops the boost operation of the boost converter if the input voltage is equal to or higher than a predetermined voltage.
Also, as an example of a technique related to a power source circuit, a discharge lamp lighting device including a battery disposed in parallel with a boost converter is provided.
Related-art techniques are disclosed in Japanese Laid-open Patent Publication Nos. 2015-53777 and 2005-108601.